Solar Orbiter

Eckart Marsch Institute for Experimental and Applied Physics (IEAP) Christian Albrechts University at Kiel, Germany

Many thanks to Richard Marsden Daniel Müller (ESA)

October 2013 SOLAR ORBITER

History Mission Proposal in Response to the ESA Call for Mission Proposals for Two Flexi-Missions History I (F2 and F3) Submitted January 27, 2000

Solar Orbiter High-Resolution Mission to the and Inner

Assessment Study Report July 2000 SCI(2000)6

Study team members: E. Marsch, Max-Planck-Institut für Aeronomie, Katlenburg-Lindau, D E. Antonucci, Osservatorio Astronomico di Torino, Pino Torinese, I P. Bochsler, University of Bern, Switzerland, CH J.-L. Bougeret, Observatoire de Paris, Meudon, F R. Harrison, Rutherford Appleton Laboratory, Chilton, UK R. Schwenn, Max-Planck-Institut für Aeronomie, Katlenburg-Lindau, D J.-C. Vial, Institut d'Astrophysique Spatiale, Université de Paris-Sud, F

ESA study scientists: B. Fleck, ESA/GSFC, Greenbelt, Maryland, USA Launch 2007 R. Marsden, ESA/ESTEC, Noordwijk, The Netherlands, NL SOLAR ORBITER

5 Workshops

2011 Telluride, USA 2012 Brugge, Belgium

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Solar Orbiter Status

• Solar Orbiter was approved on 4 October 2011 and assigned a budget within ESA’s Cosmic Vision 2015-2025 science programme. • It is now in Phase C that started end of 2012. • Memorandum of understanding with NASA (for provision of launcher and payload elements) has been signed. • The SPICE and EPD-SIS instruments remain in the payload. • System-level PDR was completed successfully in March 2012. • Instrument Principle Design Reviews (PDRs) are all completed. • Work progress is compatible with schedule for July 2017 launch. SOLAR ORBITER

How does the Sun create and control the heliosphere? Four key science questions:

Q1) How and where do the and magnetic field originate in the corona?

Q2) How do solar transients drive heliospheric variability?

Q3) How do solar eruptions produce energetic particle radiation that fills the heliosphere?

Q4) How does the solar dynamo work and drive connections between the Sun and the heliosphere? SOLAR ORBITER

Why and how does the solar magnetic field change with time? SOLAR ORBITER

Why does the solar corona emit solar wind, drive transient ejections, and show magnetic activity?

SOHO movie of the so-called Halloween storm in October 2003 SOLAR ORBITER

How does the Sun sustain and shape the Heliosphere?

McComas et al., GRL 2008 SOLAR ORBITER

Mission Overview

High-latitude Observations Launch date: January 2017 Cruise phase: 3 years Nominal mission: 3.5 years Extended mission: 2.5 years Perihelion Observations Orbit: 0.28 – 0.32 AU (perihelion) 0.74 -- 0.91 AU (aphelion) Out-of-ecliptic view: Multiple gravity assists with Venus to increase inclination out of the ecliptic to >24° (nominal mission), >34° (extended mission) Reduced relative rotation: Continuous observation of evolving structures on the solar surface and heliosphere for almost a complete solar rotation

High-latitude Observations SOLAR ORBITER

Mission Profile SOLAR ORBITER

Orbital characteristics SOLAR ORBITER

2017 Launch: Solar distance vs. time SOLAR ORBITER

2017 Launch: Solar latitude vs. time SOLAR ORBITER

How does the Sun create and control the Heliosphere?

Q1) How and where do the solar wind plasma and magnetic field originate in the corona?

Q2) How do solar transients drive heliospheric variability?

Q3) How do solar eruptions produce energetic particle radiation that fills the heliosphere?

Q4) How does the solar dynamo work and drive connections between the Sun and the heliosphere? SOLAR ORBITER

Identifying the sources of the solar wind and of the heliospheric magnetic field

Disentangling space-time structures:

- requires viewing a given active region for more than its growth time (~ 10 days) - implies going closer to the Sun SOLAR ORBITER

Where does the slow solar wind come from?

QuickTime™ and a YUV420 codec decompressor are needed to see this picture.

There are multiple sources of slow solar wind – active regions are one source.

Identifying reliably the source traits in the solar wind by the time it gets to 1 AU is extremely challenging, and can only be carried out on a statistical basis. Understanding the detailed origin can only be achieved by getting closer. SOLAR ORBITER

How do fast solar wind streams originate in coronal magnetic field structures?

polar coronal hole coronal funnel Tu, Zhou, Marsch et al., Science 2005 Tu, SOLAR ORBITER

Linking in-situ and remote-sensing observations

Correlating the remote- sensing spectroscopic with the in-situ composition measurements of the same ions is fundamental SPICE for establishing the sun- heliosphere connections. SWA/HIS SOLAR ORBITER

How does the Sun create and control the Heliosphere?

Q1) How and where do the solar wind plasma and magnetic field originate in the corona?

Q2) How do solar transients drive heliospheric variability?

Q3) How do solar eruptions produce energetic particle radiation that fills the heliosphere?

Q4) How does the solar dynamo work and drive connections between the Sun and the heliosphere? SOLAR ORBITER

How do solar transients drive heliospheric variability?

Coronal shock

How do CMEs evolve through the corona and inner heliosphere? SOLAR ORBITER

How does the Sun create and control the Heliosphere?

Q1) How and where do the solar wind plasma and magnetic field originate in the corona?

Q2) How do solar transients drive heliospheric variability?

Q3) How do solar eruptions produce energetic particle radiation that fills the heliosphere?

Q4) How does the solar dynamo work and drive connections between the Sun and the heliosphere? SOLAR ORBITER

How and where are energetic particles accelerated? SOLAR ORBITER

How do solar eruptions (flares and CMEs) produce energetic particles and radiation?

ACE data: 8.5 MeV/n O at 1 AU SOLAR ORBITER

How does the Sun create and control the Heliosphere?

Q1) How and where do the solar wind plasma and magnetic field originate in the corona?

Q2) How do solar transients drive heliospheric variability?

Q3) How do solar eruptions produce energetic particle radiation that fills the heliosphere?

Q4) How does the solar dynamo work and drive connections between the Sun and the heliosphere? SOLAR ORBITER

Probing the solar dynamo at the solar poles

Solar Orbiter will use local helioseismology to determine the unknown properties (flows and fields) of the solar interior below the poles. SOLAR ORBITER

Resolving magnetoconvection at the poles

Solar Orbiter will provide low-noise, high-spatial-resolution and full-vector measurements of the solar magnetic field near the poles. The Hinode 7o aspect angle only allows qualitative results to be obtained, but at 35o the Solar Orbiter measurements will be far improved. Also granulation tracking will then be possible and following large-scale flows. SOLAR ORBITER

SO/PHI delivers in a 2-D field of view on the visible solar surface information on

– temperature => photometry (intensity imaging) – gas flows/motions => spectroscopy (differential imaging) – magnetic fields => polarimetry (differential imaging)

Sunrise field of view: 40 arcsec x 40 arcsec

Granulation in continuum Line-of-sight velocity Longitudinal magnetic field SOLAR ORBITER

Imaging of the Sun’s pole

Simulated view of the ultraviolet corona from 35°heliolatitude. Solar Orbiter’s remote-sensing instruments and out-of-ecliptic vantage point will enable the first simultaneous measurements of the polar magnetic field and the associated structures in a polar coronal hole. (Courtesy EUI consortium.) SOLAR ORBITER

Payload: In-Situ Instruments

J. Rodríguez- Composition, timing and distribution functions of EPD Energetic Particle Detector Pacheco (E) energetic particles High-precision measurements of the heliospheric MAG Magnetometer T. Horbury (UK) magnetic field M. Maksimovic Electromagnetic and electrostatic waves, magnetic and RPW Radio & Plasma Waves (F) electric fields at high time resolution Sampling , electrons and heavy ions in the SWA Solar Wind Analyser C. Owen (UK) solar wind Payload: Remote-Sensing Instruments High-resolution and full-disk EUV imaging of the on- EUI Extreme Ultraviolet Imager P. Rochus (B) disk solar corona Multi-Element Telescope METIS for Imaging and E. Antonucci (I) Imaging and spectroscopy of the off-disk solar corona Spectroscopy Polarimetric & Helioseismic High-resolution vector magnetic field, line-of-sight PHI S. Solanki (D) Imager velocity in photosphere, visible imaging SoloHI Heliospheric Imager R. Howard (USA) Wide-field visible imaging of the solar corona and wind

Spectral Imaging of the European-led EUV spectroscopy of the solar disk and near-Sun solar SPICE Coronal Environment facility instrument corona Spectrometer/Telecope for S. Krucker (CH) STIX Imaging spectroscopy of solar X-ray emission Imaging X-rays SOLAR ORBITER

EPD-HET 4 in-situ instruments

EPD-EPT -- Detectors for energetic and solar wind particles: electrons (1eV - 20 MeV), protons (0.2 keV - 100 MeV), heavy ions (SWA, EPD)

MAG Flux Gate -- Magnetometers (DC – 64 Hz) : DC magnetic field (MAG)

-- Radio & plasma wave detectors: AC electric and magnetic fields (DC to 20 MHz / 0.1 Hz to 500 kHz) (RPW) RPW-Search Coil

RPW-ANTenna SOLAR ORBITER

EUI 3-telescope 6 Remote-sensing instruments Imager

Imagers / polarimeter / coronograph (EUI, SOLOHI, PHI, METIS) Bandwidths: Visible, UV, EUV

Spectral Imagers / Spectrometers (SPICE, STIX) Bandwidths: EUV and x-ray METIS 2-channel Coronograph SOLOHi 1-telescope SPICE Spectral Imager Imager PHI 2-telescope Imager / Polarimeter

STIX X-Ray Imager SOLAR ORBITER

Instrument locations on spacecraft

EPD : 10 units SWA: 4 units MAG: 3 units RPW: 5 units SOLAR ORBITER

EUI has three channels: • EUV full-sun (FSI) and high-resolution (HRIEUV) imagers • Ly-α high-resolution (HRILyα) imager SOLAR ORBITER

STIX

Parameter Flare diagnostics: • Timing Energy range 4 – 150 keV • Linkage Energy resolution 1 keV at 5 keV 15 keV at 150 keV

Effective area 6 cm2 Finest angular resolution 7 arcsec Field of View 2° Time resolution ≥ 0.1 s

Electron acceleration in flares: STIX Non-thermal Thermal bremsstrahlung bremsstrahlung with energies > 5 keV T ~ 10 - 40 MK SOLAR ORBITER

In-situ instruments SOLAR ORBITER

In-situ boom-mounted instruments SOLAR ORBITER

Remote-sensing instruments SOLAR ORBITER

Innovations and new technologies in space

The space environment and mission profile drive new

• Spacecraft design: −Maximal solar flux at 0.28 AU is 17,5 kWm-2 −Heat shield required (13 solar constants) −Thermoelastic distorsions of S/C and instruments −Poynting stability and coalignement of optical instruments −Solid state mass memory; payload data generation rate 120kbps −On board data processing units • Instrument design: −Optical entrance windows and filters: Heat rejection windows for PHI, X-ray entrance window for STIX, and heat rejecting mirror for SPICE −Liquid crystal variable retarders for PHI polarization, and solid crystal etalon for PHI filtergraph −New photon detectors (APS, back-illuminated CMOS) −New wave antenna deployment mechanism SOLAR ORBITER

Synergies between Solar Orbiter and other observatories

Solar Orbiter: + unique orbit (solar distance, inclination, longitude) + comprehensive payload suite - limited telemetry due to orbital characteristics

Solar Probe Plus: + unique orbit (minimal perihelion < 10 Rs) - payload mass constrained by orbital characteristics, mostly in-situ instrumentation

Near- assets: + much higher data return (SDO, ATST) - limited to Sun-Earth line

→ Depending on orbit, Solar Orbiter remote-sensing data can be complemented either by high-res/high-cadence co- spatial data from other observatories or data with additional spatial coverage, e.g. for helioseismology SOLAR ORBITER

Conclusions

Solar Orbiter will answer the question: How does the Sun create and control the Heliosphere?

• It is the first medium-class mission of ESA’s Cosmic Vision 2015-2025 science programme.

• As a joint ESA/NASA project, it is the logical next step in heliophysics after , Ulysses, and SOHO.

• It will reveal, with its 10 dedicated remote-sensing and in-situ instruments measuring from the photosphere into the solar wind, the detailed temporal and spatial connections between sun and heliosphere.